Endophyte effects on reproduction of a root‐knot nematode (Meloidogyne marylandi) and osmotic adjustment in tall fescue

Abstract

In a 2 × 2 × 2 factorial experiment, plants of one genotype of tall fescue (Festuca arundinacea) were grown in soil in pots in a glasshouse on two occasions. The treatments were either with (E+) or without (E–) infection by the fungal endophyte Neotyphodium coenophialum; with (N+) or without (N–) inoculation by the root‐knot nematode Meloidogyne marylandi; and with or without water deficit stress. In the first experiment, nematode numbers after 5 weeks had increased 10 times in the E–/N– watered pots and 22 times in the E–/N+ stressed plants. Root dry weight was decreased in all E–/N+ pots, compared with E–/N–. In contrast, nematode numbers in all E+/N+ pots decreased to nearly zero and root dry weight was unaffected. Osmotic adjustment in the growing zone of stressed plants was –0·35 MPa in E–/N– pots, but only –0·10 MPa in E–/N+ pots. Osmotic adjustment was greatest (–0·64 MPa) in E+ pots of both nematode treatments and almost no nematodes survived in the N+ pots. In the second experiment, there was complete nematode mortality in the E+ pots. Plant water relations were unaffected by treatments, however. It is concluded that endophyte‐enhanced persistence of tall fescue in M. marylandi‐infested soils that are prone to drought may be explained at least partly by endophyte protection of roots from nematode damage. Nematode inhibition by the endophyte may operate in addition to direct influences of the endophyte on enhancing drought tolerance of the host.

Microbes as interesting source of novel insecticides: A review

“…Endophytes can also have additional beneficial properties, such as accelerating seedling emergence, promoting plant growth and tolerance to adverse conditions (Harman, 2011;Companta et al, 2010). Fungal endophytes are quite common in nature and several roles have been recognised, including providing protection against herbivorous insects, plant parasitic nematodes (Elmi et al, 2000), and plant pathogens (Dingle and McGee, 2003;Wicklow et al, 2005). It has been shown that endophytic B. bassiana is compatible with both Bt and carbofuran applications used to suppress Ostrinia nubilalis .…”

The Effect of Endophytic Fungi on Nematode Populations in Summer-dormant and Summer-active Tall Fescue

“…Comparison of a transgenic nonergot alkaloidproducing strain (deletion of the dmaW gene encoding the first step of ergot alkaloid production) to the wild type strain showed endophyte-associated suppression of P. scribneri in perennial ryegrass was still evident suggesting other mechanisms might be responsible for the suppression (Panaccione et al, 2006). Reduction in root-knot nematode (Meloidogyne marylandi) population densities by ergot alkaloid-producing endophyte infected tall fescue plants has also been reported (Elmi et al, 1999). Each of these studies was conducted with summer-active tall fescue cultivars (Timper et al, 2005;Bacetty et al, 2009) or perennial ryegrass (Panaccione et al, 2006) and may not translate to effects seen with summer-dormant varieties.…”

Entomopathogenic fungal endophytes

“…Fungal endophytes have been detected in hundreds of plants, including many important agricultural commodities such as wheat (Larran et al, 2002a), bananas (Pocasangre et al, 2000;Cao et al, 2002), soybeans (Larran et al, 2002b), and tomatoes (Larran et al, 2001). Several roles have been ascribed to fungal endophytes, including providing protection against herbivorous insects (Breen, 1994;Clement et al, 1994), plant parasitic nematodes (West et al, 1988;Elmi et al, 2000), and plant pathogens (White and Cole, 1986;Dingle and McGee, 2003;Wicklow et al, 2005).…”